1. Field of the Invention
The present invention relates to a key scanning circuit, and more particularly, to a key scanning circuit designed to scan a state of a key input unit by using a current division, thereby reducing a leakage current and realizing miniaturization and simplicity of the circuit.
2. Description of the Related Art
An input device in which a plurality of keys are arranged has been used in a variety of electronic products. If a user presses a key arranged in the input device, a specific command can be input to the electronic product.
In such a key input device, on/off states of keys are usually recognized by a microprocessor. To this end, a plurality of keys are connected in a matrix configuration, and the microprocessor determines at which intersecting point a turned-on key is located by connecting an input terminal and an output terminal of the microprocessor at each intersecting point.
In the key scanning method using such a key matrix, however, a plurality of ports for recognizing the on/off states of the keys should be formed at the microprocessor. Thus, a microprocessor having much more ports should be used in order for input/output of different data, resulting in increase of a manufacturing cost and a substrate area.